Electrocardiographic patterns of exercise

JCEI / 40
Journal of Clinical and Experimental Investigations 2014; 5 (1): 40-44
doi: 10.5799/ahinjs.01.2014.01.0356
ORIGINAL ARTICLE / ÖZGÜN ARAŞTIRMA
Electrocardiographic patterns of exercise-induced ventricular arrhythmias in patients
with and without coronary artery disease
Koroner arter hastalığı olan ve olmayan hastalarda egzersize bağlı ventriküler aritminin
elektrokardiyografik özellikleri
Özgül Malçok Gürel1, Özcan Özeke2, Fırat Özcan2, Çağatay Ertan3, Zafer Büyükterzi2, Tümer Erdem Güler2,
Aytun Canga2, Veli Kaya2, Mehmet Fatih Özlü4, Dursun Aras2, Ahmet Duran Demir3
ABSTRACT
ÖZET
Objectives: This study was carried out to compare the
electrocardiographic characteristics of exercise-induced
ventricular arrhythmias (EIVA) in patients with and without
coronary artery disease (CAD).
Amaç: Bu çalışma, koroner arter hastalığı (KAH) olan
ve olmayan hastalarda egzersize bağlı ventriküler aritmi
(EBVA) ve elektrokardiyografik özelliklerini karşılaştırmak
amacıyla yapılmıştır.
Methods: The exercise tests of patients who were diagnosed to have EIVA and also underwent coronary angiography were analyzed retrospectively. The electrocardiographic patterns of EIVA in patients with and without CAD
were compared.
Yöntemler: Egzersiz testinde EBVA tespit edilen ve aynı
zamanda koroner anjiyografi uygulanan hastalar geriye
dönük olarak incelendi. KAH olan ve olmayan hastaların
EBVA’larının elektrokardiyografik özellikleri incelendi.
Results: The most common EIVA was premature ventricular contractions (PVCs) with left bundle-branch block
(LBBB) pattern and inferior axis in both groups (63% in
normal coronary artery (NCA) group and 59% in CAD
group). PVCs with right bundle-branch block (RBBB)
pattern and superior axis (33% vs. 17%, p=0.001) and
the presence of multifocal PVC were found to be more
frequent in CAD group (23% vs. 7%, p<0.001). Also, the
timing of the exercise induced PVCs (during exercise, recovery or both) did not differ between the groups.
Conclusion: The present study revealed that the most
common EIVA was PVCs with LBBB pattern and inferior
axis. Also, multifocal PVCs and the PVCs in RBBB pattern with superior axis were more common in CAD patients. J Clin Exp Invest 2014; 5 (1): 40-44
Key words: Coronary artery disease, exercise test, ventricular arrhythmias
INTRODUCTION
Ventricular arrhythmias are common findings during clinical exercise testing [1]. Exercise-induced
premature ventricular contractions (EIPVCs) may
Bulgular: Her iki hasta grubunda da en sık görülen
EBVA, sol dal bloğu (LBBB) ve inferiyor eksen içeren
erken ventriküler atımlar (EVA) idi (Normal koroner arter
(NKA) grubunda % 63 ve KAH grubunda % 59). Sağ dal
bloğu (RBBB) ve superiyor eksen şeklindeki EVA (%33
vs. %17, p=0,001) ve multifokal EVA, KAH grubunda
daha sık bulundu (% 23 vs. % 7, p<0,001). Ayrıca, egzersizin tetiklediği EVA zamanlamasında (egzersiz sırasında, dinlenme dönemi ya da her ikisinde) gruplar arasında
fark saptanmadı.
Sonuç: Bu çalışma, en sık EBVA’nın LBBB ve inferiyor
eksenli EVA’lar olduğunu ortaya koydu. Ayrıca, multifokal
EVA’lar ve RBBB ve süperiyor eksen şeklindeki EVA’lar
KAH hastalarında daha sık bulundu.
Anahtar kelimeler: Egzersiz testi, koroner arter hastalığı, ventriküler aritmi
be found in up to 30% of healthy subjects, in 60%
of those with heart disease and in all patients who
have experienced sustained ventricular tachycardia
[2]. Although an association between the occurrence
Department of Cardiology, Turgut Özal University, Ankara, Turkey
Department of Cardiology, Turkiye Yuksek İhtisas Hospital, Ankara, Turkey
3
Department of Cardiology, Acibadem Hospital, Eskisehir, Turkey
4
Department of Cardiology, Abant İzzet Baysal University, Bolu, Turkey
1
2
Correspondence: Özgül Malçok Gürel,
Dept. Cardiology, Turgut Özal University, Faculty of Medicine, Ankara, Turkey Email: ozgulmalcok@gmail.com
Received: 05.12.2013, Accepted: 04.02.2014
Copyright © JCEI / Journal of Clinical and Experimental Investigations 2014, All rights reserved
Gürel et al. ECG patterns of exercise-induced ventricular arrhythmias
of exercise-induced ventricular arrhythmias (EIVAs)
and coronary artery disease (CAD) has been described, a consensus has not existed regarding the
relation of EIVAs to CAD or to cardiovascular risk
because of the conflicting results from the available
studies [3-5]. Because arrhythmias are a part of
acute coronary syndromes, it seems reasonable to
expect this association during exercise. However,
whereas some studies have suggested an association of EIVAs with exercise-induced ischemia [6,7],
other studies refute these results [3,8,9].
Although exercise represents a well-known triggering factor of ventricular arrhythmias in patients
with CAD, mainly because of the increase in sympathetic activity and release of catecholamines, it is
unclear if the prognosis associated with EIVAs differ
based on the presence of CAD, ischemic changes
during exercise, and/or the presence of premature
ventricular contractions (PVCs) at rest (i.e., an indicator of the arrhythmic substrate) [1,10]. Some
morphologic characteristics of EIVAs have been
shown to provide prognostic information [10]. In current study, we aimed to evaluate whether there is
a relationship between the some EIVA morphologic
patterns and the presence of CAD.
METHODS
From the archive of our institution, the exercise
tests of 6446 patients were reviewed retrospectively
for the presence of ventricular arrhythmia. The exercise tests of patients who underwent coronary angiography with the EIVAs were analyzed. Patients’
demographic and clinical data were obtained from
medical records. The exercise tests of patients with
antiarrythmic drug use, heart failure, anemia, thyroid disorder, electrolyte imbalance and many artifacts on treadmill recordings were not included in
the analysis.
Study population was divided into two groups:
Group 1 included the patients without stenosis on
coronary angiography (normal coronary artery
(NCA) group) and group 2 consisted of patients with
CAD (CAD group). Coronary artery disease was defined as a >50% luminal stenosis of the left main
coronary artery or a >70% stenosis of any other major epicardial coronary arteries or major branches.
Exercise test of patients were performed on a
treadmill device (Kardiosis Ltd. Co, Ankara, Turkey)
according to the multistage Bruce protocol. During
the procedure, all standart leads were monitored
J Clin Exp Invest 41
and recorded. EIVAs were defined as the frequent
PVCs, sustained ventricular tachycardia (VT: lasting more than 30 seconds or requiring intervention)
and non-sustained ventricular tachycardia (NSVT:
3 or more consecutive PVC and less than 30 s).
We coded the morphology of EIVAs as right bundle-branch block (RBBB) pattern (positive predominance in V1 and negative predominance in V6),
left bundle-branch block (LBBB) pattern (negative
predominance in V1 and positive predominance
in V6), masquerading bundle branch block pattern
(positive predominance in both V1 and V6) or undetermined pattern (negative predominance in both
V1 and V6). The frontal plane axis was designated
as inferior (1 to 180 degrees) or superior (>180 to 0
degrees) [11].
The SPSS statistical software package (version 20.0; SPSS Inc, Chicago, Ill) was used to
perform all statistical calculations. Continuous variables were expressed as mean ± SD. Categorical
variables were expressed as numbers and percentages, and compared using the Chi²test. Two group
comparisons were performed using an unpaired ttest or nonparametric Mann-Whitney U test according to normality test results. P-value less than 0.05
were defined statistically significant.
RESULTS
The patients’ demographic and exercise related
electrocardiographic morphological features are
shown in the table. Of the 324 patients with EIVAs,
160 had angiographic evidence of CAD (Group 2)
and the remaining 164 had no significant stenosis
on coronary angiography (NCA group). The male/
female ratio was significantly higher in CAD group
than the NCA group (89% vs. 61% p<0.001).
Sustained VT or NSVT ratios and patterns
were found to be similar in CAD and NCA groups.
The most common EIVA was found to be PVCs
with LBBB pattern and inferior axis in both groups
(63% in NCA group and 59% in CAD group). PVCs
with RBBB pattern and superior axis (33% vs. 17%,
p=0.001) and the presence of multifocal PVCs were
seen more frequently in CAD group (23% vs. 7%,
p<0.001). The other forms of ventricular premature
complexes were found to be similar in both groups.
Also there was no significant difference between the
groups with regard to the timing of EIPVCs (during
exercise, recovery or both) (Table 1).
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Gürel et al. ECG patterns of exercise-induced ventricular arrhythmias
Table 1. The demographic and exercise related electrocardiographic morphological features of the patients.
Normal Coronary
Artery (n=164),
n (%)
Coronary Artery
Diseases (n=160),
n (%)
P value
55.8 ± 10.7
59.1 ± 10.1
0.258
100 (61)
143 (89)
<0.001
LBBB pattern + inferior axis (%)
103 (63)
94 (59)
0.455
LBBB pattern + superior axis (%)
RBBB pattern + inferior axis (%)
RBBB pattern + superior axis (%)
Undetermined pattern EIPVC (%)
Masquerading EIPVC (%)
Multifocal EIPVC (%)
EIPVC at only exercise phase (%)
EIPVC at only recovery phase (%)
EIPVC at both phase (%)
24 (15)
5 (3)
28 (17)
6 (4)
2 (1)
11 (7)
65 (40)
36 (22 )
64 (39)
27 (17)
12 (8)
52 (33)
7 (4)
0 (0)
37 (23)
59 (37)
33 (21)
68 (43)
0.580
0.072
0.001
0.751
0.161
<0.001
0.609
0.771
0.524
Sustained ventricular tachycardia
LBBB pattern + inferior axis (%)
LBBB pattern + superior axis (%)
RBBB pattern + inferior axis (%)
RBBB pattern + superior axis (%)
Undetermined pattern (%)
5 (3)
0 (0)
1 (0)
0 (1)
2 (1)
3 (2)
0 (0)
0 (0)
0 (0)
1 (1)
0.059
0.323
0.576
Non-sustained ventricular tachycardia
LBBB pattern + inferior axis (%)
LBBB pattern + superior axis (%)
RBBB pattern + inferior axis (%)
RBBB pattern + superior axis (%)
8 (5)
0 (89)
0 (89)
5 (3)
2 (1)
0 (89)
0 (89)
7 (4)
0.217
0.527
Age (years)
Gender (male, %)
Ventricular premature complexes
LBBB: Left bundle-branch block, RBBB: Right bundle-branch block, EIPVC: Exercise-induced premature ventricular
contraction
DISCUSSION
The main findings of this study are; 1. Most common
EIVAs were PVCs in LBBB form with inferior axis, 2.
Multifocal PVCs and the PVCs in RBBB pattern with
superior axis were more common in CAD patients.
Over the years, most cardiologists have largely
ignored PVCs during exercise testing [12]. There is
conflicting evidence about the relation of EIVAs to
CAD or to cardiovascular risk in both healthy asymptomatic subjects [5, 13, 14] and CAD patients
[8, 9, 15]. In the Framingham community cohort,
EIPVCs were associated with increased mortality
than had been previously reported [16]. Recently,
two large, prospective studies of asymptomatic
healthy individuals reported that frequent EIPVCs
are associated with increased risk of cardiovascular
mortality (>2.5 among men ) over a longer period of
follow-up exceeding 20 years [17, 18].
Although patients with suspected CAD may
have EIPVCs caused by the presence of an ischJ Clin Exp Invest emic substrate, the clinical correlates of EIPVCs in
asymptomatic individuals without such a substrate
are incompletely understood. The occurrence of EIVAs during exercise may be related to exercise induced myocardial ischemia or endothelial dysfunction, especially when combined with ST-segment
depression [19, 20]. Trejo et al. found that EIVAs
were related to the extent of CAD [21], whereas
Schweikert et al. concluded that EIPVCs were associated with a greater likelihood of thallium perfusion defects, but not associated with angiographic
presence and severity of CAD [22]. Rodriguez et al.
speculated that the electrophysiological substrate
of exercise induced ventricular tachycardia (EIVT)
in CAD patients did not differ from the substrate of
non-exercise-related VT and the re-entry was the
most probable electrophysiological mechanism [23].
It seems reasonable to assume that the presence
of EIVAs indicate a region of increased excitability
and that their relationship to exercise suggests catecholamine sensitivity. But the studies provide no
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Gürel et al. ECG patterns of exercise-induced ventricular arrhythmias
further insight into whether the EIVAs are due to
reentry, to enhanced automaticity, or to after depolarizations [1]. As noted above, their presence is not
linked to ischemia but is related in a linear fashion to
increasing age. This suggests that a change in myocardial substrate over time might have been related
to the increase in cardiovascular mortality associated with EIVAs [1]. According to several reports, in
the absence of evidence of ischemia, EIPVCs have
almost no power to predict CAD [24]. Beckerman
et al. in their review [1] and studies [14] speculated
that exercise-induced ST depression is not arrhythmogenic whereas exercise induced ST elevation
is very arrhythmogenic and associated with a high
risk, and concluded that exercise-induced ischemia
does not affect the prognostic value of EIVAs. They
do not advocate cardiac catheterization in patients
with EIVAs but with otherwise absolutely normal
exercise treadmill tests, and suggested that clinical
decisions should be made on an individual basis [1].
In the present study, we found that the multifocal PVCs and the PVCs in RBBB pattern with superior axis were seen more frequently in CAD patients
compared to NCA subjects. This finding is compatible with previous studies suggesting that the RBBBconfiguration arrhythmia, presumably originating
from the left ventricle, is often associated with left
ventricular disease, depressed ventricular function
and greater mortality compared to LBBB pattern
[10].
Idiopathic VT most commonly arises from the
right ventricular outflow tract, and less often from
the left ventricular outflow tract. Two subtypes of
outflow tract VT have been described: repetitive
monomorphic VT and paroxysmal EIVT [25, 26].
Milanes et al reported a higher prevalence of VT in
patients with CAD compared to patients with NCAs.
Of note, 80% of patients with EIVT had an abnormal ST response as well [27]. The exercise induced
non-sustained ventricular tachycardia (EINVT) has
been found not to be associated with complications
during testing or with significantly increased cardiovascular mortality within 2 years after testing [28].
We could not detect any difference in morphological
pattern of EIVT or EINVT between the groups.
The main limitations were the limited number of
patients in our population, the retrospective design
of our study and male predominance in our CAD
population. Also the electrocardiographic patterns
of EIVAs according to severity of CAD were not
analyzed.
The present study revealed that the most common EIVA was PVCs in LBBB form with inferior
axis and also showed that multifocal EIPVCs and
J Clin Exp Invest 43
the PVCs in RBBB pattern with superior axis were
more common in CAD patients compared to NCA
subjects. When evaluating the EIVAs, physicians
should search diligently for underlying structural
heart diseases, particularly CAD in adults, right ventricular dysplasia, congenital coronary anomalies,
hypertrophic or dilated cardiomyopathy, myocarditis, and catecholaminergic polymorphic ventricular
tachycardia in young patients [29]. Some electrocardiographic patterns may provide a clue for this
differential diagnosis. Future investigators should
examine how the morphology and exact quantification of EIVA affect prognosis.
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